Disc nucleus removal devices and methods

ABSTRACT

Disclosed herein are devices and methods for removing tissue. In one aspect, a device for removing tissue includes a hollow elongate member having an outer wall and a lumen, a selectively deployable tissue-cutting element extending from the hollow elongate member, and an actuation member extending through the lumen and coupled to the hollow elongate member at a location that is distal to the tissue-cutting element. Movement of the actuation member can cause the tissue-cutting element to move from the insertion configuration where the tissue-cutting element is not deployed to a tissue-cutting configuration where the tissue-cutting element is deployed such that it is radially extended relative to the insertion configuration.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a divisional of U.S. application Ser. No.11/427,848, filed on Jun. 30, 2006 and entitled “Disc Nucleus RemovalDevices and Methods,” which is hereby incorporated by reference in itsentirety.

FIELD OF THE INVENTION

The present invention relates to medical devices and methods forremoving tissue, and in particular, to medical devices and methods forremoving nucleus tissue from an intervertebral disc.

BACKGROUND OF THE INVENTION

The intervertebral discs that reside between each vertebra of the spineact as shock absorbers between the vertebrae. The disc itself consistsof a tough outer layer called the annulus, and soft inner material,called the nucleus. The soft nucleus absorbs the majority of the shockas the body moves, keeping the spine supple and supported. As one ages,both the annulus and the nucleus lose some of their cushioning ability,and a greater portion of the pressure is borne by the outside of thedisc, the annulus.

An artificial disc (also called a disc replacement, disc prosthesis orspine arthroplasty device) is a device that is implanted into the spineto imitate the functions of a normal disc (i.e., carry load and allowmotion). There are many artificial disc designs classified into twogeneral types: total disc replacement and disc nucleus replacement. Asthe names imply, with a total disc replacement, all or most of the disctissue is removed and a replacement device is implanted into the spacebetween the vertebra. With a disc nucleus replacement, only the centerof the disc (the nucleus) is removed and replaced with an implant. Theouter part of the disc (the annulus) is not removed. Disc nucleusreplacement surgery offers certain benefits compared to total discreplacement. Since a disc nucleus replacement device is designed toreplace only the nucleus of the disc, the procedure is less timeconsuming and possesses less risk to surrounding structures. Anotherbenefit of disc nucleus replacement surgery is that it results in theretention of a greater amount of tissue, which gives the disc a greaterregenerative capacity.

An important aspect of disc nucleus replacement surgery is to remove allof the nucleus material before installing the nucleus replacementdevice. In addition, care must be taken to avoid creating too large adefect in the annular wall. Incomplete or inadequate clearance of thedisc nucleus, or formation of too large an annular defect, can cause thenucleus replacement to be expelled from or to extrude from the discspace.

Accordingly, there remains a need for improved devices and methods forremoving nucleus tissue from an intervertebral disc, and in particular,devices and methods for removing nucleus tissue that minimize therequired annular defect.

SUMMARY OF THE INVENTION

The present invention provides devices and methods for removing tissue.In one aspect, a device for removing tissue is provided that includes ahollow elongate member having an outer wall and a lumen, a selectivelydeployable tissue-cutting element extending from the hollow elongatemember, and an actuation member extending through the lumen andcommunicating with the hollow elongate member at a location that isdistal to the tissue-cutting element. Movement of the actuation membercan cause the tissue-cutting element to move from the insertionconfiguration where the tissue-cutting element is not deployed to atissue-cutting configuration where the tissue-cutting element isdeployed such that it is radially extended relative to the insertionconfiguration. In use, the actuation member effects deployment of thetissue-cutting element by compression of the elongate member, and thecompression is effected by rotation of a portion of the elongate memberdistal to the tissue-cutting element. In one embodiment, the actuationmember and the elongate member are adapted to move independently of oneanother, and/or the tissue-cutting element is adapted to moveindependently of the elongate member.

The tissue-cutting element can have a variety of configurations. In oneembodiment, the tissue-cutting element can be formed on at least aportion of the hollow elongate member. In another embodiment, thetissue-cutting element can be an arm that is formed by the portion ofthe elongate member that is between adjacent slits. The at least twoadjacent slits can be formed in the outer wall of the elongate memberand located proximal to a distal end of the elongate member. The slitscan extend proximally over a distance that is less than a length of theelongate member. In other embodiments, the tissue-cutting element caninclude at least two radially-extendable arms that are formed between aplurality of slits. In alternate embodiments, the tissue-cutting elementcan be helically shaped and/or include a sharpened edge. The actuationmember can also have a variety of configurations, however in oneembodiment, the actuation member comprises at least one tether.

The device can also include a variety of other features to facilitatethe removal of tissue. In one embodiment, the lumen of the elongatemember can be adapted accommodate an irrigation fluid and/or suction. Byway of non-limiting example, a fluid input conduit and a suction conduitcan be disposed in the lumen. In another embodiment, the outer wall ofthe elongate member can be adapted to be positioned within a cannula.For example, the distal portion of the elongate member that includes thetissue-cutting element can include a ledge that abuts a shoulder of thecannula, such that the tissue-cutting element protrudes from thecannula.

The device can also include a locking mechanism that is adapted to holdthe actuation member in the actuated position. Additionally oralternatively, the device can include a steering element that is adaptedto control directional movement of the elongate member. The steeringelement can have a variety of configurations, and in one embodiment, thesteering element is a joint formed between proximal and distal ends ofthe elongate member. In another embodiment, the steering element can bea tether that extends through the lumen of the elongate member and iscoupled to the elongate member, which is flexible, at a location that isdistal to the tissue-cutting element.

Methods for the removing tissue are also disclosed herein. In oneaspect, a method for removing tissue includes positioning a tissueremoval device at a site within a disc space, the tissue removal devicehaving an elongate member with at least one selectively deployabletissue-cutting element and an actuation member. The method furtherincludes applying a force to the actuation member to cause thetissue-cutting element to move from a non-deployed insertionconfiguration to a deployed, tissue-cutting configuration in which thetissue-cutting element is radially extended relative to the insertionconfiguration, and manipulating the tissue removal device within thedisc space to cut and remove selected disc tissue. In one embodiment,the hollow elongate member is adapted move independently from theactuation member, and/or the tissue-cutting element is adapted to moveindependently of the elongate member.

The method can also include a variety of other steps to facilitatetissue removal. In one embodiment, the method can further includedelivering fluid to the tissue site through the lumen. Alternatively oradditionally, the method can include applying suction to the tissue sitethrough the lumen and/or positioning at least a portion of the elongatemember within a cannula for delivery to the disc space.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more fully understood from the following detaileddescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1A is a perspective view of one embodiment of a tissue removaldevice disclosed herein in an insertion configuration;

FIG. 1B is a perspective view of the distal end of the device of FIG. 1Ain the insertion configuration;

FIG. 1C is a perspective view of the distal end of the device of FIG. 1Bin the tissue-cutting configuration;

FIG. 1D is a perspective view of the distal end of the device of FIG. 1Cfollowing activation of a steering mechanism;

FIG. 2 is a perspective view of another embodiment of a tissue removaldevice in a tissue-cutting configuration;

FIG. 3A is a perspective view of yet another embodiment of a tissueremoval device in an insertion configuration;

FIG. 3B is a perspective view of the device of FIG. 3A positioned withina disc nucleus and in the tissue-cutting configuration;

FIG. 4 is a perspective view of another embodiment of a tissue removaldevice in a tissue-cutting configuration;

FIG. 5 is a perspective view of another embodiment of a tissue removaldevice in an insertion configuration;

FIG. 6A is a perspective view of another embodiment of a tissue removaldevice in an insertion configuration;

FIG. 6B is a perspective view of the device of FIG. 6A in thetissue-cutting configuration;

FIG. 7 is a perspective view of another embodiment of a tissue removaldevice in an insertion configuration; and

FIG. 8 is a perspective view of yet another embodiment of a tissueremoval device in an insertion configuration.

DETAILED DESCRIPTION OF THE INVENTION

Certain exemplary embodiments will now be described to provide anoverall understanding of the principles of the structure, function,manufacture, and use of the devices and methods disclosed herein. One ormore examples of these embodiments are illustrated in the accompanyingdrawings. Those of ordinary skill in the art will understand that thedevices and methods specifically described herein and illustrated in theaccompanying drawings are non-limiting exemplary embodiments and thatthe scope of the present invention is defined solely by the claims. Thefeatures illustrated or described in connection with one exemplaryembodiment may be combined with the features of other embodiments. Suchmodifications and variations are intended to be included within thescope of the present invention.

The present invention provides devices and methods for tissue removal.The tissue removal devices disclosed herein generally include anelongate member that has a tissue-cutting element formed on a distal endthereof. An actuation member can extend through the elongate member andcouple to the tissue-cutting element to control or influence theconfiguration and/or orientation thereof. Upon actuation of the member,the sections of the elongate member that contain the tissue-cuttingelements bow or deflect to expose cutting surfaces. The device can thenbe manipulated within a target site to cut tissue so that it can beremoved by suction or other means. One skilled in the art willappreciate that the device can be used to remove a variety of types oftissue, however in an exemplary embodiment the device can be used inspinal surgery to remove disc nucleus tissue.

FIGS. 1A-1D illustrate one embodiment of a tissue removal device 10 thatincludes a hollow elongate member 12 having an outer wall 11 and a lumen13, and one or more selectively deployable tissue-cutting elements 19formed on at least a portion of the hollow elongate member 12. Thedevice 10 can also include an actuation member 14 that extends throughthe lumen 13 to selectively activate the cutting elements 19. In oneembodiment, the actuation member 14 is coupled to the hollow elongatemember 12 at a location that is distal to the tissue-cutting element 19.

The elongate member 12 can have virtually any configuration that allowsit to be inserted to a surgical site. In one aspect, the member 12 isconfigured for delivery to the surgical site in a minimally invasivemanner, such as via a cannula. As shown, the member 12 is substantiallycylindrical and sufficiently strong to be inserted into tissue. Theelongate member 12 can also include features to facilitate minimallyinvasive delivery, and as shown in FIGS. 7 and 8, which will bediscussed in more detail below, the distal-most portion of the elongatemember 612, 712 can be pointed or rounded. A lumen 13 can extend throughat least a portion of the elongate member 12, and can be adapted tohouse an actuation member 14, discussed above. Further, the lumen 13 canaccommodate an irrigation fluid and/or suction delivery to the tissuesite, as will be discussed below. For example, as shown in FIGS. 3B and5, which will also be discussed in more detail below, a fluid inputconduit 260, 460 and a suction conduit 262, 462 can be disposed withinthe lumen 213, 413 to accommodate fluid delivery, and/or removal oftissue, such as by suction.

The elongate member 12 can have a variety of sizes, depending upon theintended use of the device 10. However, in one embodiment where thedevice 10 is used for disc nucleus removal, the elongate member 12 canhave an outer diameter of about 5 mm (or less) when it is in theinsertion configuration. The elongate member 12 can also be formed froma variety of materials, such as biocompatible metals, medical gradeplastics, and/or combinations thereof. Exemplary biocompatible metalscan include stainless steel, titanium, titanium alloys, cobalt chromiumalloys, nitinol, and combinations thereof. Exemplary medical gradeplastics can include nylon, polyolefins, ABS, PEEK, polysulfones,polyacetal, and combinations thereof.

At least one tissue-cutting element 19 can be formed on the distal end12 b of the member 12 that is able to be exposed (e.g., by extendingradially) when subjected to a force. FIG. 1B illustrates the device 10in which the tissue-cutting element 19 is in the insertion configurationwhere the tissue-cutting element 19 is not deployed to a tissue-cuttingconfiguration, and FIG. 1C illustrates the device 10 where thetissue-cutting element 19 is deployed such that it is radially extendedrelative to the insertion configuration. The tissue-cutting element canbe radially extended to a variety of diameters. For example, when thedevice is used to remove disc nucleus material, the device can have anouter diameter in the range of about 6 mm to 16 mm when in thetissue-cutting configuration.

The tissue-cutting element 19 can have any configuration that allows itto be configured to cut tissue (e.g., radially extend) upon theapplication of a force (e.g., compression) thereto. In one embodiment,the tissue-cutting element 19 can include at least one arm (arms 20 a-20j are shown in FIGS. 1A-1D) that is formed as a result of adjacent slits(slits 18 a-18 e are shown in FIGS. 1A-1D) in the outer surface 11 ofthe elongate member 12. The slits can have a variety of shapes, and theshape of the slits can determine the shape of the resultingtissue-cutting arm. As shown in FIGS. 1A-1D, the slits 18 a-18 e can besubstantially elongate, which can result in substantially elongate arms20 a-20 j. In other embodiments, such as shown in FIG. 5, the slits canbe formed in a spiral pattern which can result in substantially helicalarms 420 a, 420 b. Alternatively, as shown in FIGS. 6A-8, the slits(slits 518 a, 618 a, 718 a are shown) can be substantially ovular ortriangular to form arms 520 a-b, 620 a-b, 720 a-b having a complementaryshape. The slits can also have a variety of sizes, depending upon thenumber of arms desired and the diameter of the elongate member, howeverwhen the device is used to remove nucleus disc material, the slits canhave a width in the range of about 0.1 mm to 3 mm.

The arms can also have a variety of sizes depending upon the intendedapplication of the device, however the arms can generally extendproximally from a position adjacent to the distal end of the device overa distance that is less than a length of the elongate member. By way ofnon-limiting example, when the device is used to remove disc nucleusmaterial, the arms can be separated by a distance in the range of about0.1 mm to 3 mm and extend a distance in the range of 5 mm to 50 mm alongthe elongate member. One skilled in the art will appreciate that avariety of techniques can be used to form the slits, and hence the arms,however in an exemplary embodiment, the slits can be formed by a lasercutting technique or an EDM technique.

While FIGS. 1A-1D illustrates a device that has about 10 arms 20 a-20 jthat are radially disposed around the circumference of the elongatemember 12, one skilled in the art will appreciate that the device canhave any number of arms arranged in any configuration about the elongatemember. The arms can also include a variety of features to facilitatecutting of tissue. For example, in one embodiment each arm can includeat least one sharpened edge, at a leading edge of the device, that canact as a blade for cutting tissue. It is understood that the cuttingelements need not include a sharpened edge, as the device can beconfigured for use with energy-assisting cutting such as, for example,by connection to a RF generator or an ultrasound transducer. One skilledin the art will appreciate that the shape and geometry of the cuttingblades can be modified depending upon the type of cutting motiondesired, that is forward, reverse, back and forth (i.e., wanding), sideto side, or rotary cutting. For example, the angle of the cutting edgerelative to the elongate member can vary whether a forward, reverse,back and forth (i.e., wanding), side to side, or rotary cut is desired.

A variety of techniques can be used to apply a force to thetissue-cutting elements to cause them to radially extend into atissue-cutting configuration. In one embodiment, the device can includean actuation member that can extend through the elongate member andcouple to the distal most portion of the tissue-cutting element. Whilethe actuation member can have a variety of configurations, as shown inFIGS. 1A-1D, the actuation member can be two tethers 14, 16 or othercable-like element. A variety of techniques can be used to couple theactuation members to the tissue-cutting element. In one embodiment, asshown in FIGS. 1A-1D, the actuation members 14, 16 can be coupled to anend cap 22 that is positioned on the distal most end of the elongatemember 12. The actuation members 14, 16 can be coupled to the center ofthe end cap 22 to prevent biasing of the device 10. While the end cap 22can have a variety of configurations, as shown, it should be of a shapeto facilitate ease of insertion. For example, it can be rounded orbullet-shaped. The end cap 22 can be formed of a single piece or it canbe formed of a washer 26 and a nut 24. In use, a force, such as tension,can be applied to both of the actuation members 14, 16, which causes theend cap 22 to move towards the proximal end of the device 12 a andcompress the tissue-cutting element 19, thereby causing it to radiallyexpand. The elongate member 12 can then be moved independently of theactuation members 14, 16 to cut tissue. Additionally, the tissue-cuttingelements 20 a-20 j can also be moved independently of the elongatemember 12 to cut tissue. While FIGS. 1A-1D illustrate a device 10 thathas two actuation members 14, 16, in other embodiments such as FIG. 4,the device 310 can have one actuation member 314 that is disposed withinthe lumen 313 of the device 310 to effect actuation.

Referring back to FIGS. 1A-1D, the device 10 can also include a steeringmechanism to facilitate directional motion. While the steering mechanismcan have a variety of configurations, as shown the steering mechanismcan be one of the tethers 14, 16 that extend through the elongate member12 and are coupled to the distal end 12 b or end cap 22 of the device10. In other embodiments, the tether can be extend through the lumen ofthe device and be eccentrically coupled to the end cap to bias thedevice in one direction. In use, tension can be applied to one of thetethers 14,16 to cause the distal end 12 b of the elongate member 12 tobend towards the direction of the tether being activated 14, 16, asshown in FIG. 1D.

FIG. 2 illustrates another embodiment of a tissue removal device 110.The device 110 is similar to the device 10 of FIGS. 1A-1D, and includesa hollow elongate member 112 having an outer wall 111 and a lumen (notshown) extending therethrough, a selectively deployable tissue-cuttingelement 119 formed on at least a portion of the hollow elongate member112, and an actuation member (not shown) extending through the lumen andcoupled to an end cap 122 located distal to the tissue-cutting element119. The device 110 also includes a steering mechanism 128 to facilitatedirectional movement of the tissue-cutting element 119, and a handle138. However, unlike the steering mechanism 19 described above withrespect to FIGS. 1A-1D, which relies on bending the member 12 usingtethers 14,16, the steering mechanism 128 includes a joint. As shown,the joint 128 is formed on the elongate member 112, at a position thatis proximal to the tissue-cutting element 119. A variety of joints canbe used, such as the U-joint 128 shown in FIG. 2. In use, tension can beapplied to the joint 128 to bias the tissue-cutting element 119 to oneside.

A variety of techniques can be used to facilitate motion of the joint128. By way of non-limiting example, two pull wires 130, 132 can extendthrough at least a portion of the elongate member 112 and couple toelongate member 112 at a location that is distal to the joint 128.Control elements 134, 136 can be formed on the proximal end of the wires130, 132 and can be used to grip and apply tension to one of the wires130, 132 to effect directional movement of the tissue-cutting element119. While FIG. 2 shows control elements 134, 136 formed on the wires130, 132, in other embodiments, the wires can extend through a handleformed on the proximal end of the elongate member, and can be coupled toa lever, knob, or dial that can be activated to cause tension to beapplied thereto.

As noted above, the elongate member 112 can also include a handle 138that is located on the proximal end 112 a thereof to facilitatemanipulation and handling of the device 110. While the handle 138 canhave any configuration that allows a user to conveniently hold andoperate the device 110, in one embodiment the handle 138 has asubstantially elongate shape. The handle 138 can include features tofacilitate actuation of the actuation member. For example, the handle138 can include a sliding actuator lever 131 that can be coupled to theactuation member and that allows tension to be selectively appliedthereto. In alternate embodiments, rotatable knobs or dials can be usedto selectively apply tension to the actuation member. A lockingmechanism (not shown) can also be associated with the sliding actuatorlever to hold the actuation member in a desired position once tension isapplied.

The handle 138 can also include a driving mechanism to facilitatemovement of the tissue-cutting element 119 to effect cutting of tissuewhen it is in the tissue-cutting configuration. For example, as shown,the handle 138 can include a rotatable knob 140 to effect rotationalmovement of the tissue-cutting element 119. Additionally, the handle caninclude features to facilitate the removal of tissue, such as a port fordelivering suction and/or irrigation to the elongate member, or it canbe adapted to couple to an external suction and/or irritation port. Oneskilled in the art will appreciate the variety of features that can beformed on the handle.

FIGS. 3A-8 illustrate other embodiments of a tissue removal device 210,310, 410, 510, 610, 710. The device 210 of FIGS. 3A-3B is similar to thedevice 10 of FIGS. 1A-1D, and includes a hollow elongate member 212having an outer wall 211 and a lumen 213, and a selectively deployabletissue-cutting element 219 formed on at least a portion of the hollowelongate member 212. The device 210 also includes an actuation member214 that extends through the lumen 213 and is coupled to an end cap 222located distal to the tissue-cutting element 219. However, the device210 shown in FIGS. 3A-3B, unlike the device 10 of FIGS. 1A-1D, has asingle cutting arm 220 a that is formed as a result of the formation oftwo slits (slit 118 a is shown) in the elongate member 212. Such asingle cutting arm 220 a can be used for directional cutting. As shownin FIG. 3B, when a force (e.g., tension or a rotational force applied tothreaded members) is applied to move the device 210 from the insertionconfiguration to the tissue-cutting configuration, the tissue-cuttingelement 119 is radially extended in only one direction, and used to cuttissue in a certain area, for example by a back and forth motion or arotary motion. Once cut, the tissue can be removed from the tissue siteby the application of fluid and/or suction through fluid input conduit260 and/or suction conduit 262 that are disposed within the lumen 213,as noted above.

FIG. 4 illustrates another embodiment of a tissue removal device 310.The device 310 is also similar to the device 10 of FIGS. 1A-1D, andincludes a hollow elongate member 312 having an outer wall 311 and alumen 313, and a selectively deployable tissue-cutting element 319formed on at least a portion of the hollow elongate member 312. Thedevice 310 also includes an actuation member 314 that extends throughthe lumen 313 and is coupled to an end cap 322 located distal to thetissue-cutting element 319. However, unlike the device 10 in FIGS.1A-1D, the device 310 can have two opposed tissue-cutting elements 320a, 320 b that are formed as a result of two slits (slit 318 a is shown).The device 310 can also have an actuation member 314 that is threadablymated to end cap 322. As the actuation member is rotated, a compressiveforce will be applied to end cap 322, causing the arms 320 a, 320 b tobow out. This results in the device 310 having a bulb-shapedconfiguration when in the tissue-cutting configuration. Although theactuation of the embodiment shown in FIG. 4 is described with respect torotation of a threaded member, one skilled in the art will understandthat tension can alternatively be applied to the actuation member.

FIG. 5 illustrates yet another embodiment of a tissue removal device410. The device 410 is similar to the device 10 of FIGS. 1A-1D, andincludes a hollow elongate member 412 having an outer wall 411 and alumen 413, and a selectively deployable tissue-cutting element 419formed on at least a portion of the hollow elongate member 412. Thedevice 410 also includes an actuation member 414 that extends throughthe lumen 413 and is coupled to an end cap 422 located distal to thetissue-cutting element 419. However, unlike the device 10 in FIGS.1A-1D, the device 410 includes helically shaped cutting elements 420 a,420 b that are formed as result of spirally cut slits. The cuttingmember can be formed as a result of a single helix, or numerous helicesformed in or extend from the elongate member. In use, force (e.g.,tension or a rotational force applied to threaded members) is applied tocompress the outer walls of the helix, thereby causing expansionthereof. When in the tissue-cutting configuration, the device 410 can besubstantially tubular in shape, having a substantially constantdiameter. Additionally, and when moved to cut tissue (e.g., by rotationof the helical cutting elements 420, 420 b), the helically-shapedcutting elements 420 a, 420 b can help initiate tissue movement into thedevice 410.

FIGS. 6A-6B illustrate yet another embodiment of a tissue removal device510. The device 510 is similar to the device 10 of FIGS. 1A-1D, andincludes a hollow elongate member 512 having an outer wall 511 and alumen 513, and a selectively deployable tissue-cutting element 519formed on at least a portion of the hollow elongate member 512. Thedevice 510 also includes an actuation member 514 that extends throughthe lumen 513 and is coupled to an end cap 522 located distal to thetissue-cutting element 519. However, unlike the device 10 in FIGS.1A-1D, the device 510 includes two substantially ovular slits (slit 518a is shown) that form arms 520 a, 520 b. In use, a force is applied tocompress the arms 520 a, 520 b and the device 510 moves from theinsertion configuration (FIG. 6A) to the tissue-cutting configuration(FIG. 6B), and the arms 520 a, 520 b extend radially to cut tissue.

The device 510 can also include features that facilitate insertionwithin a cannula 550. While a variety of features can be used, as showneach elongate member 512 can include opposed ledges 582, 584 that areformed thereon at a location that is proximal to the tissue-cuttingelement 519. The ledges 582, 584 are adapted to abut correspondingshoulders 572, 574 that are formed on a cannula 550. One skilled in theart will appreciate that the ledges and shoulders can have a variety ofsizes, depending upon the intended use of the device. In use, and as aforce (i.e., tension) is applied to the actuation member 514, the ledge582, 584 is pressed against the shoulder 572, 574 to facilitate theradial expansion of the tissue-cutting element 519.

FIG. 7 illustrates yet another embodiment of a tissue removal device610. The device 610 is similar to the device 10 of FIGS. 1A-1D, andincludes a hollow elongate member 612 having an outer wall 611 and alumen 613, and a selectively deployable tissue-cutting element 619formed on at least a portion of the hollow elongate member 612. Thedevice 610 also includes an actuation member 614 that extends throughthe lumen 613 and is coupled to an end cap 622 located distal to thetissue-cutting element 619. However, unlike the device 10 in FIGS.1A-1D, the device 610 includes two substantially triangular slits (slit618 a is shown) that form arms 620 a, 620 b. The device 610 can alsoinclude features that facilitate insertion within a cannula 650. Asnoted above, the elongate member 612 of the device 610 can include asubstantially rounded distal end. Additionally, and similar to thedevice 510 of FIGS. 6A-6B, each elongate member 612 can include opposedledges 682, 684 that are formed thereon at a location that is proximalto the tissue-cutting element 619. The ledges 682, 684 are adapted toabut corresponding shoulders 672, 674 that are formed on a cannula 650.In use, and as a force (e.g., tension) is applied to the actuationmember 614, the ledge 682, 684 is pressed against the shoulder 672, 674to facilitate the radial expansion of the tissue-cutting element 619.

FIG. 8 illustrates yet another embodiment of a tissue removal device710. The device 710 is similar to the device 10 of FIGS. 1A-1D, andincludes a hollow elongate member 712 having an outer wall 711 and alumen 713, and a selectively deployable tissue-cutting element 719formed on at least a portion of the hollow elongate member 712. Thedevice 710 also includes an actuation member 714 that extends throughthe lumen 713 and is coupled to an end cap 722 located distal to thetissue-cutting element 719. However, unlike the device 10 in FIGS.1A-1D, the device 710 includes two substantially triangular slits (slit718 a is shown) that form arms 720 a, 720 b. The device 710 can alsoinclude features that facilitate insertion within a cannula 750. Asnoted above, the elongate member 712 of the device 710 can include asubstantially pointed distal end. Additionally, and similar to thedevice 510 of FIGS. 6A-6B, each elongate member 712 can include opposedledges 782, 784 that are formed thereon at a location that is proximalto the tissue-cutting element 719. The ledges 782, 784 are adapted toabut corresponding shoulders 772, 774 that are formed on a cannula 750.In use, and as a force (i.e., tension) is applied to the actuationmember 714, the ledge 782, 784 is pressed against the shoulder 772, 774to facilitate the radial expansion of the tissue-cutting element 719.

One skilled in the art will appreciate that each of the various designsprovides for disc removal with cutting surfaces. The cutting surfacescan be located along the leading edge(s) of the blade(s) and can betapered to a relatively sharp cutting tip or plane. The helically shapedcutting elements allow for cutting via rotary motions prompting thecollection of the loose disc tissue in the central portion of the deviceand for aspiration with the central cannula. The multiple blades of thehelical shaped cutting element provide for the exposure of additionalcutting surfaces for each rotation when compared to the dual bladedevice shown in FIG. 4. This added exposure reduces the number ofrotations required to remove tissue. In addition, the multi-bladehelical device allows for one blade to pull/tension the tissue and thesecond to cut under tension, this can also enhance the ability to removetissue.

The devices disclosed herein can be used to remove tissue from, forexample, the nucleus of a disk. While the method is described inconnection with device of FIGS. 3A-3B, a person skilled in the art willappreciate that various other devices can be used. In one embodiment,and following preparation of the patient and surgical site as is knownin the art, the device can be inserted to the target tissue, e.g., thenucleus of the disc, via a hole in the annular wall. As shown in FIG.3B, the device 210 can be inserted through a cannula 250 to position thedevice 210 within the disc nucleus 254. The device 210 is preferablyinserted in the insertion configuration, as shown in FIG. 3A. Such aninsertion configuration is particularly advantageous in that itminimizes the size of the annular defect and enables the use ofminimally invasive surgical techniques. Once inserted into the discnucleus material, and if the device includes a steering mechanism, thesteering mechanism can be activated to further position the devicewithin the disc at the site of the tissue to be removed.

Once the device 210 is positioned within the nucleus 254, a force can beapplied to the actuation member 214. For embodiments where the actuationmember is a tether 214, the tether 214 can be pulled in the proximaldirection to cause the tissue-cutting element to radially expand to thetissue-cutting configuration. Depending upon the configuration of thedevice, the tension can be applied to the tether directly, or bymovement of a lever, dial, or knob formed on a handle of the device. Asa result, the device 210 moves from the insertion configuration to thetissue-cutting configuration, where the tissue-cutting arm 220 a isradially expanded relative to the elongate member 212, as shown in FIG.3B. The actuation member can then optionally be locked in position usinga locking mechanism to maintain the radial expansion of thetissue-cutting element.

Once the device is in the tissue-cutting configuration, the device canbe moved to cut tissue, and it can be steered, as appropriate, to reachareas of the nucleus that require removal of tissue. Depending upon thetype of tissue cut desired, the device can be rotated, moved forward, ormoved in reverse. One skilled in the art will appreciate that movementof the device can be effected by directly moving the elongate member, bymoving a lever, dial, or knob on the handle of the device, and/or byactivating an energy source to deliver energy to the tissue-cuttingelement. As the tissue is being cut, or alternatively, once all of thetissue is cut, the tissue fragments can be removed from the disc. Whilea variety of removal techniques can be used, in one embodiment and stillreferring to FIG. 3B, suction and/or irrigation can be applied through afluid input conduit 260 and a suction conduit 262 that are disposedwithin the lumen 213. In other embodiments, the elongate member can beremoved and a separate tissue removal device can be inserted into thenucleus space to clear the tissue.

Following the removal of the tissue, the locking mechanism canoptionally be unlocked and the force that is applied to the actuationmember released. This causes the tissue-cutting element to radiallyretract back to the insertion configuration. The device can then beremoved from the tissue, leaving behind a substantially tissue-freenucleus space and minimizing the size of the annular defect.

One skilled in the art will appreciate further features and advantagesof the invention based on the above-described embodiments. Accordingly,the invention is not to be limited by what has been particularly shownand described, except as indicated by the appended claims. Allpublications and references cited herein are expressly incorporatedherein by reference in their entirety.

What is claimed is:
 1. A method for removing tissue, comprising:positioning a selectively steerable tissue removal device at a sitewithin a disc space, the tissue removal device having an elongate memberwith at least one selectively deployable tissue-cutting element andfirst and second tethers extending through the tissue removal device andeccentrically coupled at a distal end of the tissue cutting element,wherein a distal end of the tissue removal device is configured to besteered in multiple directions relative to a longitudinal axis of thetissue removal device by applying a force to at least one of the firstand second tethers; applying a force to the first and second tethers tocause the at least one tissue-cutting element to move from anon-deployed insertion configuration to a deployed, tissue-cuttingconfiguration in which the tissue-cutting element is radially extendedrelative to the insertion configuration; and manipulating the tissueremoval device within the disc space to cut and remove selected disctissue.
 2. The method of claim 1, wherein the hollow elongate member isadapted to move independently from the first and second tethers.
 3. Themethod of claim 1, wherein the tissue-cutting elements are adapted tomove independently from the elongate member.
 4. The method of claim 1,further comprising delivering fluid to the tissue site through a lumenformed in the elongate member.
 5. The method of claim 4, furthercomprising applying suction to the tissue site through the lumen.
 6. Themethod of claim 1, further comprising positioning at least a portion ofthe elongate member within a cannula for delivery to the disc space. 7.A method for removing tissue, comprising: positioning a selectivelysteerable tissue removal device at a site within a disc space, thetissue removal device having an elongate member with at least oneselectively deployable tissue-cutting element and first and secondtethers extending through the tissue removal device, wherein a distalend of the tissue removal device is configured to be steered in multipledirections relative to a longitudinal axis of the tissue removal deviceby applying a force to at least one of the first and second tethers;applying a force to the first and second tethers to cause the at leastone tissue-cutting element to move from a non-deployed insertionconfiguration to a deployed, tissue-cutting configuration in which thetissue-cutting element is radially extended relative to the insertionconfiguration; and manipulating the tissue removal device within thedisc space to cut and remove selected disc tissue.
 8. The method ofclaim 7, wherein the hollow elongate member is adapted to moveindependently from the first and second tethers.
 9. The method of claim7, wherein the tissue-cutting elements are adapted to move independentlyfrom the elongate member.
 10. The method of claim 7, further comprisingdelivering fluid to the tissue site through a lumen formed in theelongate member.
 11. The method of claim 10, further comprising applyingsuction to the tissue site through the lumen.
 12. The method of claim 7,further comprising positioning at least a portion of the elongate memberwithin a cannula for delivery to the disc space.